With the continuous scaling of feature sizes in the semiconductor device technology, conventional lithography faces extreme challenges since the pace of the development of new lithographic tools lags behind the pace of reduction in the minimum feature size. While manipulation of images such as use of sublithographic assist features (SLAFs) and optical proximity effect correction has provided some relief to assist printing of images on a photoresist with improved fidelity and at a reduced critical dimension (CD), i.e., the minimum printable feature size, line width variations within a chip and across a substrate plague attempts to reliably and repeatably print lithographic images having a dimension close to the minimum printable feature size. Such challenge is inherent in the lithography currently employed in the semiconductor industry since any lithography tool has an inherent non-uniformity in image production due to mechanical factors such as lens aberration and chemical factors in the uniformity of the photoresist coating.
Further, significant delays have occurred in the development of lithographic tools that were planned to provide adequate lithographic capabilities beyond 45 nm node of the semiconductor technology. Such lithographic tools employ extreme ultraviolet (EUV) lithography or electron beam (e-beam) lithography, neither of which has provided a commercially viable and reliable lithography system. However, for the scaling of features sizes to continue in the semiconductor industry, reliable methods of producing feature sizes less than 45 nm, and preferably less than 30 nm is required.
In view of the above, there exists a need for a novel method for reliably providing feature sizes that are smaller than those that are currently available.
Further, as the dimension of feature sizes shrink in semiconductor devices, small variations in the feature size induce substantial variations in device performance. Thus, there exists a need for lithographic methods for printing constant line width features independent of dimensional variations in an image of a developed photoresist.